A lot has changed since the last time
I could see Apple licensing to Dell and HP. A few things have changed since the last time.
One is that a vendor would only have to license the OS, no full motherboard licensing required or hardware issues. Dell/HP could build as usual and then have OS X and a BTO option. Heck, they could offer Windows *and* OS X as an option.
There are some interesting Apple patents in regards to the possibility of being able to run multiple OSs at the same time, which would totally rock.
So this would be *much* easier and inexpensive for the major vendors. Also, Apple makes more money now by selling OS upgrades, iLife and other software, as well as iPods, music downloads, video downloads, Airports, iSights, etc...
If a person was going to buy a Dell, and on check out see that they have a $50-$100 option to buy it with OS X, who loses?
And of course for special promos, Dell could include iLife or other bundling.
This is much different from some bit player making a huge investment in going in as a Mac cloner.